The invention relates to a method of precise position determination.
Such a method is known from Beutler, G., D. A. Davidson, R. Langley, R. Santerre, P. Vanicek, D. E. Wells (1984) in "Some Theoretical and Practical Aspects of Geodetic Positioning using Carrier Phase Difference Observations of GPS Satellites," Reports by the Zimmerwald satellite observation station, No. 14 and Department of Surveying Engineering Technical Report No. 109, University of New Brunswick, Fredericton, Canada, pp. 1-41, 78, 79, as relative static positioning using the GPS Navstar satellite navigation system.
An overview of the GPS system, the measurement variables and relative positioning is given in the Company Prospectus "GPS--The Surveying System of the Future" Wild Heerbrugg Ltd., Heerbrugg, Switzerland, 1987.
A navigation system based on the Doppler method for various installed radio satellite systems is known from EP-B 0,167,683.
In the known method for relative static positioning, measurement times of about one hour are required with five available transmitters to determine the relative position of two points 10 km apart to an accuracy in the region of one cm.
Approaches to speeding up the measurement by means of an optimized evaluation method are known from Frei, E., G. Beutler "Some Considerations Concerning an Adaptive, Optimized Technique to Resolve the Initial Phase Ambiguities", Proceedings of the Fifth International Geodetic Symposium on Satellite Positioning, Mar. 15-17, 1989, pp. 671-686, Las Cruces, New Mexico; Remondi, B. W. "Performing Centimeter Level Surveys in Seconds with GPS Carrier Phase: Initial Results". Proceedings of the Fourth International Geodetic Symposium on Satellite Positioning, Apr. 18-May 2, 1986, pp. 1229-1249, Austin, Tex.; Beutler, G., W. Gurtner, M. Rothacher, U. Wild, E. Frei "Relative Static Positioning with the Global Positioning System: Basic Technical Considerations" lecture to the IAG General Meeting, Edinburgh, August 1989; and V. Ashkenazi, P. I. Summerfield "Rapid static and kinematic GPS surveying: with or without cycle slips". Land and Minerals Surveying, Vol. 7, No. 10, 10/89, pages 489-494 (GB Journal). The content of the quoted references is part of the disclosure of this application.
The quasi-kinematic method described therein according to Remondi (loc. cit.) results in a saving in measurement time only in the case of a sequence of measurements at different points and is dependent on a receiver being able to be transported from point to point in radio contact with the transmitters, without interference. However, in general this condition is difficult to adhere to and difficult to check. Ashkenazi and Summerfield (loc. cit) solve this problem by repeated measurement at the first measurement point. The method specified by Frei and Beutler for rapid resolution of the phase ambiguity uses only the a posteriori rms error in a method according to the precharacterizing clause of claim 1 and tests all the complete alternative phase ambiguities located within an interval of plus or minus three times the a posteriori rms errors around the actual phase ambiguities for the magnitude of the rms error of the positioning vector.
With measurement times of a few minutes, this method is adequate only if 7 to 8 satellites can be received or if measurements from 5 to 6 satellites can be used on two frequencies (L1 and L2).
It is also known, from Beutler et al. for it to be possible to achieve an improvement in the method described be repeated measurement with a time interval.